In recent years, new techniques for DNA and RNA sequencing have been developed. Conventionally, methods using electrophoresis have been used for DNA and RNA sequencing, which involve the steps of: preparing cDNA fragment samples, which are synthesized from cDNA fragments or RNA fragments for sequencing through reverse transaction reaction; inducing dideoxy reaction by a known Sanger method; and measuring molecular weight separation development patterns by electrophoresis for analysis.
In contrast to this, recently, methods, which enable a plurality of DNA fragment samples to be fixed on a substrate to acquire sequencing information in parallel, have been developed, improving remarkably analysis speed of bases. These techniques enable a plurality of samples to be analyzed in parallel by arranging a cluster of amplified nucleic acid sequences to be analyzed on a plate to measure using two-dimensional image sensor. For example, a nonpatent literature 1 discloses a technique, which involves the step of inducing PCR reaction using a primer fixed on the substrate to form a cluster of an amplified gene fragments on the substrate. Moreover, a nonpatent literature 2 discloses a technique, which involves the steps of inducing emulsion PCR reaction to amplify and fix the nucleic acid sequences on the surfaces of microparticles and fixing the microparticles on the plate.
For these super-parallel sequencer, the formation of a cluster is an important step because the formation of a high-density cluster increases sequencing information, which can be acquired from an image sensor at a time, while an increase in the number of gene fragments per cluster achieves the enhancement of signal intensify, improvement in reliability of sequencing information, and simplification of a detector.